Method and catalyst for removing contaminants from hydrocarbonaceous fluids using a copper-group via metal-alumina catalyst

ABSTRACT

There is provided a method and catalyst for removing catalyst-poisoning impurities or contaminants such as arsenic, iron and nickel from hydrocarbonaceous fluids, particularly shale oil and fractions thereof. More particularly there is provided a method of removal of such impurities by contacting the fluids with a copper-Group VIA metal-alumina catalyst. For example, a copper-molybdenum-alumina catalyst may be used as a guard bed material in a step preceding most refining operations, such as desulfurization, denitrogenation, catalytic hydrogenation, etc.

This is a divisional of copending application Ser. No. 524,064, filed onAug. 17, 1983 and now U.S. Pat. No. 4,539,001.

BACKGROUND OF THE INVENTION

This invention relates to a method and catalyst for removingcatalyst-poisoning impurities or contaminants such as arsenic, iron andnickel from hydrocarbonaceous fluids, particularly shale oil andfractions thereof. More particularly, the invention relates to a methodof removal of such impurities by contacting the fluids with acopper-Group VIA metal-alumina catalyst. The catalyst may be used as aguard bed material in a step preceding most refining operations, such asdesulfurization, denitrogenation, catalytic hydrogenation, etc.

Due to scarcity of other hydrocarbon fuels and energy resources ingeneral, shale oil and other hydrocarbonaceous fluids such as thosederived from coal, bituminous sands, etc., are expected to play anincreasing role in the production of commercial hydrocarbon fuels in thefuture. Substantial effort has been devoted to the development ofcost-efficient refining techniques for the processing of thesehydrocarbonaceous fluids. Frequently, these fluids contain contaminantsthat poison and deactivate expensive and sensitive upgrading catalystsused in hydrogenation and other refining steps to which thesehydrocarbonaceous fluids must be subjected before they can besatisfactorily used as sources of energy. In addition, the removal ofcontaminants such as arsenic may be necessary for environmentalprotection if the hydrocarbonaceous fluids are employed as fuels, asthese contaminants form poisonous compounds.

The prior art has included several methods of removing arsenic fromhydrocarbonaceous fluids, such as that described in U.S. Pat. No.2,778,779 to Donaldson issued on June 14, 1952. Such methods haveincluded the use of metal oxides to remove arsenic from streams ofnaturally occurring crude oil.

Other processes have been developed for the removal of arsenic presentin the parts per billion range from naphthas in order to protectsensitive reforming catalysts. Unfortunately, such processes cannot beapplied to shale and other hydrocarbonaceous fluids which often havearsenic concentrations as high as 60 ppm.

Also known, are washing processes employing aqueous caustic solutions toprecipitate arsenic salts from the hydrocarbonaceous fluid and extractthem into the aqueous phase. See, e.g. U.S. Pat. No. 2,779,715 to Murrayissued on Jan. 29, 1957 and D. J. Curtin et al, "Arsenic and NitrogenRemoval during Shale Oil Upgrading", A.C.S. Div. Fuel Chem., No. 23(4),9/10-15/78. These processes, however, are relatively expensive, cause asubstantial amount of fluid to be lost to the aqueous phase, contaminatethe hydrocarbon fluid with aqueous solution and present a problem withregard to the disposal of waste caustic solution.

Many patents have issued which are directed to use of a metallic oxideand/or sulfide catalyst such as iron, nickel, cobalt or molybdenum oxideor sulfide or composites thereof on an alumina carrier to remove arsenicand other contaminants from shale oil. See, e.g. U.S. Pat. No. 4,003,829to Burget et al issued on Jan. 18, 1977, U.S. Pat. No. 4,141,820 toSullivan issued on Feb. 27, 1979 and U.S. Pat. No. 3,954,603 to Curtin,U.S. Pat. No. 3,804,750 to Myers and U.S. Pat. No. 4,046,674 to Young.While these processes are effective, they employ relativelysophisticated and relatively expensive catalysts which considerablycontribute to the processing costs of shale oil.

U.S. Pat. No. 4,354,927 to Shih et al issued on Oct. 19, 1982 describesthe removal of catalyst poisoning contaminants such as arsenic andselenium from hydrocarbonaceous fluids particularly shale oil by contactwith high-sodium alumina in the presence of hydrogen; saturation ofconjugated diolefins is also effected.

Japan Pat. Nos. 5,6095-985; 5,6092-991; and 5,4033,503 to ChiyodaChemical Engineering Company of Japan describe Group IB catalysts fordemetalation; however, these utilize specific supports (not alumina).

The Bearden, Jr. et al U.S. Pat. No. 4,051,015 describes a copperchloride demetalation catalyst.

OBJECTS

It is an object of this invention to provide an improved catalyst andmethod for removing arsenic from hydrocarbonaceous fluids such as shaleoil.

It is another object of this invention to provide an improved catalystand method for removing arsenic from a hydrocarbonaceous fluid having arelatively high arsenic content.

It is a further object of this invention to provide a catalyst andprocess for removal of arsenic which does not entail use of an aqueousphase and mixing of said aqueous phase with the hydrocarbon.

It is yet another object of this invention to provide an improvedcatalyst and method for removing arsenic and other contaminants fromhydrocarbonaceous fluids, which method is inexpensive and does notsubstantially contribute to the processing cost of the fluids.

These and other objects will become apparent from the specificationwhich follows.

SUMMARY

In accordance with one aspect of the invention, there is provided amethod for reducing the content of at least one of arsenic, iron andnickel in a hydrocarbonaceous fluid by contacting the fluid with aparticulate catalyst consisting essentially of an oxide or sulfide ofcopper and an oxide or sulfide of a Group VIA metal on a porous aluminasupport in the presence of hydrogen under sufficient metal reducingconditions. Such metal reducing conditions may involve, e.g., atemperature ranging from about 400° to 900° F., a pressure ranging fromabout 100 to 3000 psig, and a LHSV of from about 0.1 to 10. By means ofthe metal reducing process of the present invention, a relatively smallamount of hydrogen may be consumed while removing a relatively largeamount of metals.

According to another aspect of the invention, there is provided aparticulate catalyst consisting essentially of an oxide or sulfide ofcopper and an oxide or sulfide of a Group VIA metal on a porous aluminasupport, wherein the total weight of the oxides or sulfides of copperand the oxides or sulfides of the Group VIA metal are present in anamount ranging from about 20 to 75 weight percent, based on the totalcatalyst, the remainder of the catalyst being essentially alumina. Thiscatalyst is particularly suitable for reducing the content of at leastone of arsenic, iron and nickel in a hydrocarbonaceous fluid bycontacting the fluid with the catalyst in the presence of hydrogen undersufficient metal reducing conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the removal of arsenic from shale oil by acopper-molybdenum-alumina catalyst as compared with other demetalationcatalysts.

FIG. 2 is a graph showing the removal of nickel from shale oil by acopper-molybdenum-alumina catalyst as compared with other demetalationcatalysts.

FIG. 3 is a graph showing the removal of iron from shale oil by acopper-molybdenum-alumina catalyst as compared with other demetalationcatalysts.

FIG. 4 is a graph showing demetalation vs. hydrogen consumption forshale oil with a copper-molybdenum-alumina catalyst as compared withother demetalation catalysts.

DETAILED DESCRIPTION

The Group VIA metals referred to herein correspond to the elements ofGroup VIA of the Periodic Chart of the Elements. The Periodic Chartreferred to herein is that version officially approved by the UnitedStates National Bureau of Standards (NBS) and the International Union ofPure and Applied Chemists (IUPAC), the elements of Group VIA beingchromium (Cr), molybdenum (Mo) and tungsten or wolfram (W). PreferredGroup VIA metals are molybdenum and tungsten, especially molybdenum.

Examples of preferred catalysts according to the present inventioncontain from about 20 to 65, most especially 38 to 46, weight percentCuO and from about 4 to 12, most especially 7 to 9 weight percent MoO₃.Catalysts in accordance with the present invention may have a porevolume within the range of about 0.4 cc/g and 0.8 cc/g and a surfacearea within the range of 150 to 250 m² /g.

By way of example, retorted shale oil can be partially upgraded bycontacting the demineralized ("desalted") oil with a CuMo/Al₂ O₃ guardchamber catalyst in the presence of hydrogen at temperatures of500°-700° F. In this process, a 42 wt. % copper oxide; 8 wt. % molybdenaon alumina catalyst shows demetalation activity equal to or better thanconventional hydrotreating catalysts, but requires less hydrogenconsumption. As discussed more fully hereinafter, the catalyst hashigher nickel removal activity than other (nickel-containing) catalysts.This may be especially significant for in-situ derived shale oils whichtend to have higher nickel contents than conventionally retorted oils.Since the catalyst has some hydrogenation activity, it effectivelylowers the conjugated diolefin content at mild conditions--somethingthat a Ni/Al₂ O₃ or Cu/Al₂ O₃ catalyst cannot achieve if the feedstockis high in sulfur (≧0.5 wt. %).

Retorted shale oil contains a large number of trace metals such as As,Fe, Ni, V, Co, Se and Zn; As and Fe are the predominant trace elements(>20 ppm). These metals present several processing and product problems:

some arsenic compounds in shale oil are water soluble and can causepipeline corrosion;

when shale oil is upgraded by delayed coking, most of the metals arerejected in the coke, resulting in a lower quality coke;

upgrading catalysts are irreversibly poisoned by metals deposition;

when burned directly as a fuel, shale oil has potential As₂ O₃ emissionproblems.

As mentioned previously, there are many methods reported in theliterature for arsenic removal, adsorption, extraction, thermaltreatment, and chemical additives. Relative to metals in petroleum,arsenic in shale oil is very reactive. Commercial hydrotreatingcatalysts, when fresh, can easily reduce the arsenic and other metals inshale oil to less than 0.1 ppm under normal hydrotreating conditions(T≧725° F. and LHSV≦0.8). Since metals poison the catalyst'shydrotreating activity, upstream metals removal is preferred.

Most guard chamber operations are carried out in the presence ofhydrogen. Although arsenic removal is relatively insensitive to hydrogenpartial pressure (i.e. k α (P/P_(o))⁰.4) in the 400-2200 psi range,plugging problems have been encountered at lower pressures (<1000 psi).The major catalysts--nickel, cobalt, iron or copper --have poorhydrogenative activity at lower temperatures (≦400° F.) andconsequently, cannot eliminate the fouling problems.

The invention may be practiced in a guard bed chamber preferably havinga fixed bed of porous particulate material, but a moving bed may also beused. An example of such a particulate material is acopper-molybdenum-alumina catalyst.

The guard bed may be situated in a guard chamber, a closed metal vesselcapable of being pressurized. The particles must be capable of promotingdeposition of the contaminants thereon when contacted by thehydrocarbonaceous feed under a reducing atmosphere provided by hydrogenat a pressure between 100 and 3000 psig, preferably between 400 and 2500psig, and at a temperature between 400° and 900° F., preferably between500° and 750° F.

The hydrocarbonaceous feed is preferably admixed with hydrogen at aratio ranging from 1000 to 10,000 standard cubic feet (scf) of H₂ perbarrel (b) of feed and preferably 2000 to 5000 scf of H₂ /b of feed andthe admixed feed is contacted with the particles for a time sufficientto reduce the arsenic and other contaminant content to acceptablelevels.

The quantity of material in the guard bed should be sufficient to keepthe Liquid Hourly Space Velocity (LHSV), measured in units of volumetricflow rate of feed per unit volume of catalyst, between the values of 0.1and 10 and preferably between those of 0.5 and 3. This LHSV rangecorresponds to a residence time for the feed in the guard bed rangingbetween 0.1 and 10 hours and preferably 0.3 to 2 hours.

The invention may be further illustrated by the Examples which follow:

EXAMPLE 1 Catalyst Preparation [42% CuO-8% MoO₃ -50% Al₂ O₃ ]

A catalyst was prepared in the following manner: 211 ml. of solutioncontaining 73.0 grams ammonium heptamolybdate (81.5% MoO₃) were blendedin a muller-mixer with 535 grams of alpha alumina monohydrate powder, aproduct commercially available as Kaiser Substrate Alumina (SA) fromKaiser Chemicals. Then 454 grams of cupric carbonate (68.85% CuO) wereblended into the mixture, after which 200 ml. water were added. Themixture was extruded to one-thirty second inch diameter cylinders, driedat 250° F. and calcined two hours at 800° F.

The catalyst had the following properties:

    ______________________________________                                        Density, g/cc                                                                 Packed             0.73                                                       Particle           1.41                                                       Real               4.57                                                       Pore Volume (PV), cc/g                                                                           0.489                                                      Surface Area, m/g  208                                                        Avg. Pore Diameter, Å                                                                        94                                                         Pore Size Distribution                                                        % of PV in Pores of                                                            0-50Å Diameter                                                                              17                                                          50-100            22                                                         100-150            21                                                         150-200            23                                                         200-300            11                                                         300+               6                                                          ______________________________________                                    

EXAMPLE 2

The catalyst of Example 1 was used in five runs for the demetalation ofOccidental Shale Oil. Data for this example are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    Demetalation of Occidental Shale Oil over (CuMo/Al.sub.2 O.sub.3)                        CHG 1    2   3    4   5                                            __________________________________________________________________________    Reactor Conditions                                                            Temperature, °F.                                                                  --  504  556 608  650 701                                          Pressure, psig                                                                           --  2200 2200                                                                              2200 2200                                                                              2200                                         LHSV, vff/hr/vcat                                                                        --  1.8  1.8 1.8  1.9 2.0                                          Days on Stream                                                                           --  1.3  2.1 2.9  3.6 4.4                                          TLP Properties                                                                Gravity, °API                                                                     23.0                                                                              23.2 24.6                                                                              24.8 25.1                                                                              26.4                                         Hydrogen, wt. %                                                                           12.04                                                                            12.10                                                                              12.40                                                                             12.35                                                                              12.41                                                                             12.70                                        Nitrogen, wt. %                                                                           1.61                                                                              1.47                                                                               1.46                                                                              1.35                                                                               1.32                                                                              1.29                                        Sulfur, wt. %                                                                             0.67                                                                              0.57                                                                               0.52                                                                              0.50                                                                               0.37                                                                              0.25                                        Arsenic, ppm                                                                             20.0                                                                              12.0 11.0                                                                              9.6  6.4 3.3                                          Iron, ppm  68.0                                                                              4.1  3.3 2.2  1.4 0.9                                          Nickel, ppm                                                                              11.0                                                                              10.0 9.4 8.4  4.7 1.5                                          H.sub.2 Consumption, scf/b                                                               --   28  --  197  244 429                                          __________________________________________________________________________

Three catalysts are compared for processing Occidental shale oil. Shell324 and Harshaw Ni-3266E are feld to be relatively active commercialcatalysts for demetalation. Key results are shown in FIGS. 1-4. Theresults indicate:

The catalyst of Example 1 is less active than Shell 324 fordearsenation, but more active than Harshaw Ni-3266E;

The catalyst of Example 1 is more active than the other catalysts foriron and nickel removal. The approximate 100° F. improvement in ironremoval activity is especially significant as iron is the mostpredominant trace metal in shale oil. Nickel removal is especiallyimportant for in-situ generated shale oils which tend to have highernickel concentrations.

The demetalation/hydrogen consumption selectivity of the catalyst ofExample 1 is better than Harshaw Ni-3266E or Shell 324. The selectivitycould probably be improved by optimizing the molybdenum content in thecatalyst of Example 1.

About 70% of the arsenic removed was retained on the catalyst. This issimilar to the amount retained on nickel-containing catalysts. Thearsenic compounds are speculated to be reacting with the copper to formstable complexes. Copper-arsenic complexes are abundant in nature (e.g.,enargite-3CuS.As₂ S₅) and are often a by-product of copper smeltingoperations. (Note Kirk-Othmer, Encyclopedia of Chemical Technology,Second Edition, Vol. 2, p. 721.

Features of the process of the present invention include the following:

Uses copper-Group VIA metal-alumina catalyst for demetalation.

Retains arsenic on catalyst-probably in the form of copper-arseniccomplexes.

Has higher iron and nickel removal activities than nickel-containingdemetalation catalysts.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives and variationswill be apparent to those skilled in the art in light of the foregoingdescription. Accordingly, it is intended to embrace all suchalternatives and variations that fall within the spirit and scope of theappended claims.

What is claimed is:
 1. A particulate catalyst for dearsenating anddemetallizing a hydrocarbonaceous fluid consisting essentially of fromabout 38 to 46 weight percent CuO and 7 to 9 weight percent MoO₃ on aporous alumina support, wherein the total weight of the CuO and the MoO₃are present in an amount ranging from about 20 to 75 weight percent,based on the total catalyst, the remainder of the catalyst beingessentially alumina.
 2. The catalyst of claim 1 which has a pore volumewithin the range of about 0.4 cc/g and 0.8 cc/g and a surface areawithin the range of 150 to 250 m² /g.